Turbines



March 25, 1958 .3. H. FORSYTH ET AL 2 TURBINES Filed July 24, 1956 nitedStates Patent TURBINES George Howard Forsyth, James Stevens, and JosephHenry Aubrey, London, England, assignors to Viekers- Armstrongs(Engineers) Limited, London, England, a British company Application July24, 1956, Serial No. 599,800

Claims priority, application Great Britain July 28, 1955 3 Claims. (Cl.253-39) This invention relates to turbines.

According to the present invention there is provided an axial flowturbine having a rotor, an inner casing around the rotor, a nozzle boxat the high pressure end of the rotor, and an outer casing around andsupporting both the inner casing and the nozzle box, the rotor having ashaft that is passed through glands at the high pressure and lowpressure ends of the outer casing, wherein the nozzle box has a sleevethat is integral therewith and which is passed through the high pressureend of the outer casing and carries the gland at this end of the casing,the high pressure end of the outer casing having an inlet and outlet forfluid that serves to pressurise the nozzle box, there being also aninlet for delivering working fluid to the nozzle box, and wherein thenozzle box has a wall integral therewith which extends from the nozzlebox to the outer casing to which the wall is sealed, the wall separatingthat part of the outer casing through which pressurising fluid flowsfrom the part of the outer casing that contains the inner casing.

For a better understanding of the invention and to show how the same maybe carried into effect, reference will now be made to the accompanyingdrawing in which the single figure is a longitudinal sectional elevationof a steam turbine.

The turbine is of the axial flow type and has a rotor 1 that carrieseight rings 2 of blades 3 and is located within a pressure casing 4. Thecasing 4 has an inlet 5 and an outlet 6 at the high pressure end of thecasing 4. The inlet 5 is for connection to the main boiler (not shown)of the steam turbine installation and the outlet 6 leads to asuperheater (not shown) of the installation. An inlet 7 for highlysuperheated steam delivered by the superheater passes concentricallythrough the outlet 6 to a nozzle box 8 disposed around the high pressureend of the rotor 1. The nozzle box 8 has a sleeve 9 that is integraltherewith and extends through a bush 10 mounted in a boss 11 at the highpressure end of the casing 4. It will be understood that the sleeve 9,bush 10 and boss 11 are formed concentrically with the shaft 28 of therotor 1.

Y The bush 10 is sealed to the boss 11 by welding 12 and the sealbetween the sleeve and the bush is formed by Ramsbottom rings 13.

A frusto-conical portion 14 integral with the nozzle box 8 divergestherefrom towards the low pressure end of the casing 4. The portion 14has an outwardly directed flange 15 at the wider end thereof and thehigh pressure side of this flange 15 abuts against a circumferentialshoulder 16 around the inside of the casing 4. A ring 17 keyed to theinside surface of the casing 4 abuts against the wider end of thefrusto-conical portion 14. A split ring 18 that is secured in acircumferential recess 19 in the inner surface of the casing 4 locatesthe ring 17 against movement away from the frusto-conical portion 14.The ring 18 is bolted to the ring 17.

An inner casing 20 of cylindrical form and split longitudinally into twohalves 20A, 20B is supported by the ice ring 17. The two halves 20A, 20Bof the inner casing 20 are held together by bolts 21 and this casing 20carries seven rings of nozzles 22, each ring of nozzles 22 being locatedbetween two adjacent rings 2 of blades 3 on the rotor 1. The ring 17, atthe low pressure side thereof, has an inwardly directed flange 23 andthe inner casing 20 has an outwardly directed rib 24 thatis locatedbetween the flange 23 on the ring 17 and the wider end of thefrusto-conical portion 14. The seating between the rib 24 and the flange23 on the ring 17 forms a seal 25. The rib 24 of the inner casing 20 issecured to the ring 17 by studs 26.

The low pressure end of the pressure or outer casing 4 has an exhaust 27that leads to another turbine (not shown) of the installation oralternatively through a valve (not shown) to the condenser (not shown)of the installation.

The rotor shaft 28 passes through the low pressure end of the outercasing 4 and the latter carries a gland 29 for preventing leakage ofsteam along this part of the shaft 28. At the high pressure end of theturbine the shaft 28 passes through a gland 30 carried by the sleeve 9.The shaft 28 is supported at each end of the turbine by bearings 35.

The outer or pressure casing 4 is formed in two parts 4A, 4B, beingsplit vertically (i. e. in a plane perpendicular to the axis of therotor 1) to the low pressure side of the split ring 18. At the split 31in the casing each part 4A, 4B is provided with a flange 32 and thesetwo flanges 32 are bolted together.

In operation of the turbine described above high pressure steam which isslightly superheated passes in via the inlet 5 and pressurises theexterior of the nozzle box 8, the frusto-conical portion 14, and thatpart 9A of the sleeve 9 that is within the pressure casing 4. Thepressurising steam then passes from the casing 4 via the outlet 6, ishighly superheated in the superheater and is returned to the turbine viathe inlet 7 and flows to the nozzle box 8. Steam flows from the nozzles33 of the nozzle box 8 through the successive rings of blades 3 andnozzles 22, to the space 34 between the inner and outer casings 20 and 4and thence to the exhaust 27.-

That part of the inner casing 20, that is to the high pressure side ofthe rib 24 is, on the outside thereof, subjected to the pressure of thesteam emerging from the nozzles 33 of the nozzle box 8, as also is theinside of the frustoconical portion 14. That part of the inner casing20, that is to the low pressure side of the rib 14 is, on the outsidethereof, subjected to the pressure of the steam emerging from the lastring 3 of the blades 2 of the rotor 1, i. e., to the exhaust pressure ofthe turbine.

We claim:

1. An axial flow turbine having a rotor, an inner casing around therotor, a nozzle box at the high pressure end of the rotor, an outercasing around and supporting both the inner casing and the nozzle box, ashaft upon which the rotor is mounted, first and second glands at thehigh pressure and low pressure ends respectively of the outer casing andthrough which glands the shaft is passed, a sleeve integral with thenozzle box, the sleeve being passed through the high pressure end of theouter casing and carrying the first gland, the high pressure end of theouter casing having an inlet and an outlet for fluid that serves topressurise the nozzle box and there being also an inlet for deliveringworking fluid to the nozzle box, a conical-shaped wall integral with thenozzle box, the wall extending and diverging from the nozzle box to theouter casing to which the wall is sealed, the wall separating that partof the outer casing through which pressurising fluid flows from the partof the outer casing that contains the inner casing, a circumferentialshoulder on the inside of the outer casing, an outwardly directedfiange. on the wider end of the conical-shaped wall, the shoulder beingon the high pressure side of said flange, a ring abutting against thelow pressure. side of said flange, and rneans' connectingtheouterperipheral: surface of the ring to the outer casing andconnecting'the ring to the inner" casing so that the latter is supportedby the ring.

2. A turbine according to claim 1, wherein a groove is formed around theinside surface of the outer casing, the groove being adjacent the lowpressure side of said ring, the connecting means including a .split ringinserted in the groove and abutting against the first-mentioned ring tocause the latter to abut against said flange.

. 3. A turbine according to claim 1, wherein the inner casing is ofcylindrical form and includes. between its ends an outwardly directedcircumferential rib, said ring including on the low pressure sidethereof an inwardly directed flange, the turbine further comprisingmeans connecting the rib to theringwith the rib abutting against thehigh pressure side of said inwardly directed flange.

References Cited in the file of this patent UNITED STATES PATENTS2,391,786 Kenney Dec. 25, 1945 2,429,936 Kenney et a1. Oct. 28, 19472,527,446 Jenks et a1 Oct. 24, 1950

